[Issue Q&A] Moderna Halved... Tangled Vaccine Schedule

Maintain Vaccination Interval for Grade 12 Students and High School Staff
Vaccination Interval Extended from 4 to 6 Weeks... Authorities Say "No Problem"

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Kwon Deok-cheol, First Deputy Head of the Central Disaster and Safety Countermeasures Headquarters (Minister of Health and Welfare), and Jung Eun-kyeong, Director of the Korea Disease Control and Prevention Agency (from right), are entering and greeting at the joint briefing by the Ministry of Health and Welfare and the Korea Disease Control and Prevention Agency held on the afternoon of the 9th at the Korea Disease Control and Prevention Agency in Cheongju, Chungbuk, to announce the COVID-19 vaccine introduction and vaccination plans. [Photo by Yonhap News]

[Asia Economy Reporter Lee Chun-hee] The schedule for COVID-19 vaccinations has undergone a major change as the planned delivery of 8.5 million doses of the Moderna vaccine this month was cut in half. The messenger RNA (mRNA) vaccine schedule, which was originally unified at 4 weeks, has been changed to 6 weeks, and the possibility of vaccinating young people with the AstraZeneca (AZ) vaccine has been raised again. The following is a Q&A regarding these matters.

Q. If the supply of Moderna vaccines in August is disrupted, will the second dose schedule for those who received the first dose also change?

A. Currently, the 6.9 million people in their 50s who are receiving their first dose of mRNA vaccines will all have their vaccination interval changed to 6 weeks. Therefore, if they received their first dose on the first day of vaccination, the originally scheduled second dose date of the 23rd will be postponed by two weeks to the 6th of next month. The total number of people whose vaccination interval will be delayed by two weeks includes 15.26 million aged 18-49, 1.99 million for local government autonomous second and third doses, and 320,000 for workplace vaccinations, totaling 24.53 million people including those in their 50s.

If the supply shortage of Moderna vaccines prolongs further, the 21.97 million people who have not yet received their first dose may have to postpone their first dose from the currently scheduled dates.

However, 620,000 high school seniors and high school staff and 100,000 other college entrance exam candidates will maintain the current vaccination intervals of 3 weeks and 4 weeks respectively, considering the university entrance exam schedule. Also, 580,000 elementary grade 3 to middle school grade 3 staff will have their vaccination interval changed to 5 weeks instead of 6 weeks to complete vaccination before the second semester starts.

Q. Is it safe to change the mRNA vaccine interval from 4 weeks to 6 weeks?

A. The authorized vaccination intervals for Pfizer and Moderna vaccines are 3 weeks and 4 weeks respectively. Last month, the health authorities held an expert vaccination committee meeting and allowed the interval to be extended up to 6 weeks depending on vaccine supply and vaccination conditions.

The authorities state that vaccination with the same interval is being carried out overseas without any issues. Currently, the UK is vaccinating Pfizer, Moderna, and AZ vaccines all at 8-week intervals. Germany uses intervals of 3-6 weeks for Pfizer and 4-6 weeks for Moderna, and Canada allows intervals up to 16 weeks.

However, unlike the previous extension of the AZ vaccine interval to 12 weeks to enhance preventive effects, no scientific evidence has been presented for this change.

Jung Eun-kyung, Director of the Korea Disease Control and Prevention Agency, explained, "There is no clinical trial data specifically on vaccination intervals," but added, "When pharmaceutical companies conducted clinical trials, data for second doses given at intervals around 6 weeks were also included, not just the 3-week interval data, and the clinical trial efficacy evaluation was based on that."

Moderna COVID-19 Vaccine [Image Source=AP Yonhap News]

Q. Is achieving herd immunity still feasible even if Moderna vaccines do not arrive?

A. The government currently plans to achieve herd immunity by reaching 36 million people (70%) with the first dose by September and 70% with the second dose by November. To achieve this, an additional 14.63 million first doses and 28.11 million second doses are required as of today. At least 43 million additional doses need to be secured.

However, excluding Moderna, there are still 157.91 million doses of vaccines scheduled for delivery this year, so the government believes that even if Moderna supply is disrupted, achieving herd immunity itself will not be significantly affected. For Pfizer, which has a stable supply, 49.715 million doses are still scheduled for delivery. Even if there is some delay, achieving the 70% target with Pfizer vaccines alone is possible.

The government plans to additionally import 12.035 million doses of Pfizer and AZ vaccines this month, 42 million doses next month, and complete the import of 90 million doses in the fourth quarter.

Q. If mRNA vaccines are insufficient, is there a possibility that the AZ vaccine, currently limited to those aged 50 and above, will be administered to younger age groups?

A. In the worst-case scenario, this cannot be ruled out. Regarding this question, Director Jung responded, "The AZ vaccine is authorized for those aged 18 and above," and added, "Vaccination can be carried out within the authorized age range depending on vaccine supply and epidemic situations." This means that if vaccine supply becomes critical, lowering the age limit for AZ vaccine administration, currently allowed only for those aged 50 and above, is possible.

Currently, the AZ and Janssen vaccines, developed as viral vector vaccines, are not allowed for those under 49 due to the risk of thrombocytopenia syndrome (TTS) being assessed as higher than the preventive effect. Janssen, which requires only one dose and is convenient, can be administered to those under 49 only if two doses are difficult, but even then, only those aged 30 and above can receive it. As a result, the AZ vaccine has become unpopular to the extent that leftover vaccine reservations are always available.

This content was produced with the assistance of AI translation services.